Well. I come from a family where politeness is really big so just from learning from example, I've always been taught not to take a compliment and lower myself in some sort of way. Which is partially why I have such terrible self-esteem and it's taken years to override even a little bit of that. Especially when it comes to people with poor self-esteem, just because you say something doesn't mean they'll suddenly believe it. If anything it reminds them of what they think they lack and they'll feel the need to correct what you think. So give them a little slack

Also, if you're expecting some kindness back I would kindly reconsider why you are giving the compliment in the first place.